Option 1 (preferred) - Dab some white spirit (mineral spirit) on a rag and wipe off the glue (sometimes needs a bit of rubbing with the soaked rag). Nail polish remover works similarly, but might not be strong enough for residue from really old stickers / facing.
Option 2 (If the bat is dry and you usually oil the face) - Apply some linseed oil to the face, lay the bat down flat for a while (10-15 mins). The oil weakens the glue's bond. Then scrape off the mess with a straight blunt edge (like the edge of a plastic giftcard or an old credit card)